From the viewpoint of enzyme technology, oxygenases, which incorporate molecular oxygen directly into organic substrates, are particularly intriguing since selective, direct oxygenation of organic substrates has traditionally been an unresolved challenge to organic chemistry. We have focused on oxygenase-catalyzed heteroatom oxygenation, epoxidation, hydroxylation, and ketonization of simple organic substrates (Fig. 1). These represent basic, synthetically important reactions. In all cases, the reactions involve highly stereo and regio selective insertions of molecular oxygen into organic substrates. Although we illustrate these three oxyfunctionalization reaction types for a few specific cases, work in progress indicates that several other enzymes, heretofore considered simple hydroxylases, also readily carry out these three processes with regio and stereo specificity.